Xcode预置Sinppets知多少

Objective-C, Sinppets, Xcode

前言

NSHipster本周的主题是《Xcode Snippets》，并将他们常用的Snippets放在了GitHub，又引来很多粉丝疯狂的Star，我也过去观望了一下，其实内容不多，而且也没有什么太多的亮点，我觉得只要你平时注意积累和整理自己的Snippets，效果一定比从别人那里Fork来用要好得多。什么？你还不知道Snippets是什么？那你弄清楚了再来看！

其实我平时也不太注意Sinppets的积累和整理，所以决定从现在起开始。在积累自己的Sinppets前，我先大致看了一下Xcode预置的Sinppets，发现不少我曾经千百次敲的代码Sinppets里面都有，所以觉得有比较写成文章记录一下。

Sinppets

现在就按顺序将Xcode预置的Sinppets过一遍。

C Block typedef

Shortcut: typedefBlock

Code:

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typedef <#return type#>(^<#block name#>)(<#arguments#>);

C Inline Block as Variable

Shortcut: inlineBlock

Code:

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<#Return Type#>(^<#Block Name#>)(<#Parameter Types#>) = ^(<#Parameters#>) {
    <#Code#>
};

C typedef

Shortcut: typedef

Code:

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typedef <#existing#> <#new#>;

C++ Class Declaration

Shortcut: classdef

Code:

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class <#class name#> {
  <#instance variables#>
public:
  <#member functions#>
};

C++ Class Template

Shortcut: templateclass

Code:

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template <<#template parameters#>>
class <#class name#> {
  <#instance variables#>
public:
  <#member functions#>
};

C++ Function Template

Shortcut: templatefunction

Code: 

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template <<#template parameters#>>
<#return type#> <#function name#>(<#function parameters#>) {
  <#statements#>
}

C++ Namespace Definition

Shortcut: namespace

Code:

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namespace <#namespace name#> {
  <#declarations#>
}

C++ Try / Catch Block

Shortcut: try

Code: 

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try {
  <#statements#>
} catch (<#catch parameter#>) {
  <#statements#>
}

C++ Using Directive

Shortcut: using namespace

Code:

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using namespace <#namespace name#>

Core Data Basic Fetch

Shortcut:

Code:

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NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"<#Entity name#>" inManagedObjectContext:<#context#>];
[fetchRequest setEntity:entity];
NSError *error = nil;
NSArray *fetchedObjects = [<#context#> executeFetchRequest:fetchRequest error:&error];
if (fetchedObjects == nil) {
    <#Error handling code#>
}
[fetchRequest release];

比较奇怪的是所有Core Data相关的Snippets都没有提供Shortcut，有知道的朋友麻烦留言告诉我。

Core Data Fetch with a Predicate

Shortcut:

Code:

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NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"<#Entity name#>" inManagedObjectContext:<#context#>];
[fetchRequest setEntity:entity];
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"<#Predicate string#>", <#Predicate arguments#>];
[fetchRequest setPredicate:predicate];
NSError *error = nil;
NSArray *fetchedObjects = [<#context#> executeFetchRequest:fetchRequest error:&error];
if (fetchedObjects == nil) {
    <#Error handling code#>
}
[fetchRequest release];

Core Data Fetch with Sorting

Shortcut:

Code:

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NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"<#Entity name#>"
inManagedObjectContext:<#context#>];
[fetchRequest setEntity:entity];
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"<#Sort key#>"
ascending:YES];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[fetchRequest setSortDescriptors:sortDescriptors];
NSError *error = nil;
NSArray *fetchedObjects = [<#context#> executeFetchRequest:fetchRequest error:&error];
if (fetchedObjects == nil) {
    // Handle the error
}
[fetchRequest release];
[sortDescriptor release];
[sortDescriptors release];

Core Data Property Accessors

Shortcut:

Code:

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- (<#Property type#> *)<#Property name#>
{
    [self willAccessValueForKey:@"<#Property name#>"];
    <#Property type#> *tmpValue = [self primitiveValueForKey:@"<#Property name#>"];
    [self didAccessValueForKey:@"<#Property name#>"];
    return tmpValue;
}
            
- (void)set<#Capitalized property name#>:(<#Property type#> *)value
{
    [self willChangeValueForKey:@"<#Property name#>"];
    [self setPrimitiveValue:value forKey:@"<#Property name#>"];
    [self didChangeValueForKey:@"<#Property name#>"];
}

Core Data Propery Validation

Shortcut:

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- (BOOL)validate<#Capitalized property name#>:(id *)valueRef error:(NSError **)outError
{
    BOOL validationResult = YES;
    <#Validation code#>
    return validationResult;
}

Core Data Scalar Property Accessors

Shortcut:

Code: 

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- (<#Property type#>)<#Property name#>
{
    [self willAccessValueForKey:@"<#Property name#>"];
    <#Property type#> *tmpValue = <#Property name#>;
    [self didAccessValueForKey:@"<#Property name#>"];
    return tmpValue;
}
- (void)set<#Capitalized property name#>:(<#Property type#>)value
{
    [self willChangeValueForKey:@"<#Property name#>"];
    <#Property name#> = value;
    [self didChangeValueForKey:@"<#Property name#>"];
}

Core Data To-Many Relationship Accessors

Shortcut:

Code:

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- (void)add<#Capitalized relationship name#>Object:(<#Relationship destination class#> *)value
{    
    NSSet *changedObjects = [[NSSet alloc] initWithObjects:&value count:1];
    [self willChangeValueForKey:@"<#Relationship name#>" withSetMutation:NSKeyValueUnionSetMutation usingObjects:changedObjects];
    [[self primitiveValueForKey:@"<#Relationship name#>"] addObject:value];
    [self didChangeValueForKey:@"<#Relationship name#>" withSetMutation:NSKeyValueUnionSetMutation usingObjects:changedObjects];
    [changedObjects release];
}
- (void)remove<#Capitalized relationship name#>Object:(<#Relationship destination class#> *)value
{
    NSSet *changedObjects = [[NSSet alloc] initWithObjects:&value count:1];
    [self willChangeValueForKey:@"<#Relationship name#>" withSetMutation:NSKeyValueMinusSetMutation usingObjects:changedObjects];
    [[self primitiveValueForKey:@"<#Relationship name#>"] removeObject:value];
    [self didChangeValueForKey:@"<#Relationship name#>" withSetMutation:NSKeyValueMinusSetMutation usingObjects:changedObjects];
    [changedObjects release];
}
- (void)add<#Capitalized relationship name#>:(NSSet *)value
{    
    [self willChangeValueForKey:@"<#Relationship name#>" withSetMutation:NSKeyValueUnionSetMutation usingObjects:value];
    [[self primitiveValueForKey:@"<#Relationship name#>"] unionSet:value];
    [self didChangeValueForKey:@"<#Relationship name#>" withSetMutation:NSKeyValueUnionSetMutation usingObjects:value];
}
- (void)remove<#Capitalized relationship name#>:(NSSet *)value
{
    [self willChangeValueForKey:@"<#Relationship name#>" withSetMutation:NSKeyValueMinusSetMutation usingObjects:value];
    [[self primitiveValueForKey:@"<#Relationship name#>"] minusSet:value];
    [self didChangeValueForKey:@"<#Relationship name#>" withSetMutation:NSKeyValueMinusSetMutation usingObjects:value];
}

Do-While Statement

Shortcut: dowhile

Code:

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do {
  <#statements#>
} while (<#condition#>);

Enumerate Index Set

Shortcut:

Code:

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NSUInteger index = [<#index set#> firstIndex];
while (index != NSNotFound) {
    // Do something with index
    index = [<#index set#>  indexGreaterThanIndex:index];
}

Enumerate Index Set In Reverse

Shortcut:

Code:

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NSUInteger index = [<#index set#> lastIndex];
while (index != NSNotFound) {
    // Do something with index.
    index = [<#index set#> indexLessThanIndex:index];
}

同样，已上两个也没有提供Shortcut。

Enumeration Declaration

Shortcut: enumdef

Code:

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enum <#enumeration name#> {
  <#enumerator1#> = <#value1#>,
  <#enumerator2#> = <#value2#>
};

For Statement

Shortcut: for

Code:

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for (<#initialization#>; <#condition#>; <#increment#>) {
  <#statements#>
}

GCD: Dispatch After

Shortcut: dispatch_after

Code:

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double delayInSeconds = 2.0;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayInSeconds * NSEC_PER_SEC));
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
    <#code to be executed on the main queue after delay#>
});

GCD: Dispatch Once

Shortcut: dispatch_once

Code:

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static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
    <#code to be executed once#>
});

If Statement

Shortcut: if

Code:

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if (<#condition#>) {
  <#statements#>
}

If-Else Statement

Shortcut: ifelse

Code:

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if (<#condition#>) {
  <#statements-if-true#>
} else {
  <#statements-if-false#>
}

Objective-C Autoreleasing Block

Shortcut: @autoreleasepool

Code:

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@autoreleasepool {
    <#statements#>
}

Objective-C Catch Block

Shortcut: @catch

Code: 

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@catch (<#exception#>) {
    <#handler#>
}

Objective-C Category

Shortcut: @interface-category

Code:

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@interface <#class name#> (<#category name#>)
@end

Objective-C Category Implementation

Shortcut: @implementation-category

Code:

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@implementation <#class#> (<#category name#>)
<#methods#>
@end

Objective-C Class Declaration

Shortcut: @interface

Code:

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@interface <#class name#> : <#superclass#>
@end

Objective-C Class Extension

Shortcut: @interface-extension

Code:

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@interface <#class name#> ()
@end

Objective-C Class Implementation

Shortcut: @implementation

Code:

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@implementation <#class#>
<#methods#>
@end

Objective-C dealloc Method

Shortcut: dealloc

Code:

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- (void)dealloc
{
    <#deallocations#>
}

Objective-C Fast Enumeration

Shortcut: forin

Code: 

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for (<#type *object#> in <#collection#>) {
    <#statements#>
}

Objective-C Finally Block

Shortcut: @finally

Code:

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@finally {
    <#handler#>
}

Objective-C init Method

Shortcut: init

Code:

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- (id)init
{
    self = [super init];
    if (self) {
        <#initializations#>
    }
    return self;
}

Objective-C KVO: Observe Value For Keypath

Shortcut: observeValueForKeyPath

Code:

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- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
    if (context == <#context#>) {
        <#code to be executed upon observing keypath#>
    } else {
        [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
    }
}

Objective-C KVO: Values affecting Key

Shortcut: keyPathsForValuesAffecting

Code: 

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+ (NSSet *)keyPathsForValuesAffecting<#Dependent Key#>
{
    return [NSSet setWithObjects:@"<#key1#>", nil];
}

Objective-C Protocol Definition

Shortcut: @protocol

Code:

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@protocol <#protocol name#> <NSObject>
<#methods#>
@end

Objective-C Try / Catch Block

Shortcut: @try

Code:

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@try {
    <#statements#>
}
@catch (NSException *exception) {
    <#handler#>
}
@finally {
    <#statements#>
}

###Struct Declaration

Shortcut: structdef

Code:

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struct <#struct name#> {
  <#instance variables#>
};

Switch Statement

Shortcut: switch

Code:

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switch (<#expression#>) {
  case <#constant#>:
    <#statements#>
    break;
  default:
    break;
}

Test Method

Shortcut: test

Code:

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- (void) test<#Name#> {
    <#statements#>
}

###Union Declaration

Shortcut: uniondef

Code:

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union <#union name#> {
  <#instance variables#>
};

While Statement

Shortcut: while

Code:

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while (<#condition#>) {
  <#statements#>
}

Objective-C NSCoding initWithCoder Method

Shortcut: initWithCoder

Code:

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- (id)initWithCoder:(NSCoder *)coder
{
    self = [super initWithCoder:coder];
    if (self) {
        <#initializations#>
    }
    return self;
}

Objective-C NSView initWithFrame Method

Shortcut: initWithFrame

Code:

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- (id)initWithFrame:(NSRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        <#initializations#>
    }
    return self;
}

总结

复制粘贴真累，上面贴出来这么长，其实很多根本就不用记，比如：for， typedef等，可以当成Xcode代码补齐功能 ， 但有的使用可能需要注意一些条件，如：init，dealloc，如果你习惯于一写方法就先写-(id)或-(void)，那么再打init，dealloc就千呼万唤使不出来了，我就躺枪了，你呢？ 还有像 observeValueForKeyPath 和 keyPathsForValuesAffecting 确实不知道，不知道有没有常用KVO的将这两个方法自己又加一遍Snippets？

当然Snippets在添加时可以设置如支持的平台（OS X or iOS），语言环境以及使用的位置（Completion Scopes）,用系统预置的Snippets就不用管那么多了，反正苹果会将这些设置为最合理的就是了，我们自己添加Snippets时就得多考虑一下这些设置的参数了。