Xcode预置Sinppets知多少

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 typedof

Shortcut: typedofBlock

Code:

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

C Inline Block as Variable

Shortcut: inlineBlock

Code:

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

C typedef

Shortcut: typedef

Code:

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

C++ Class Declaration

Shortcut: classdef

Code:

class <#class name#> {
  <#instance variables#>

public:
  <#member functions#>
};

C++ Class Template

Shortcut: templateclass

Code:

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

C++ Function Template

Shortcut: templatefunction

Code:

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

C++ Namespace Definition

Shortcut: namespace

Code:

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

C++ Try / Catch Block

Shortcut: try

Code:

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

C++ Using Directive

Shortcut: using namespace

Code:

using namespace <#namespace name#>

Core Data Basic Fetch

Shortcut:

Code:

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:

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:

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:

- (<#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:

Code:

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

Core Data Scalar Property Accessors

Shortcut:

Code:

- (<#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:

- (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:

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

Enumerate Index Set

Shortcut:

Code:

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

Enumerate Index Set In Reverse

Shortcut:

Code:

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:

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

For Statement

Shortcut: for

Code:

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

GCD: Dispatch After

Shortcut: dispatch_after

Code:

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:

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

If Statement

Shortcut: if

Code:

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

If-Else Statement

Shortcut: ifelse

Code:

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

Objective-C Autoreleasing Block

Shortcut: @autoreleasepool

Code:

@autoreleasepool {
    <#statements#> }

Objective-C Catch Block

Shortcut: @catch

Code:

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

Objective-C Category

Shortcut: @interface-category

Code:

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

Objective-C Category Implementation

Shortcut: @implementation-category

Code:

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

<#methods#>

@end

Objective-C Class Declaration

Shortcut: @interface

Code:

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

@end

Objective-C Class Extension

Shortcut: @interface-extension

Code:

@interface <#class name#> ()

@end

Objective-C Class Implementation

Shortcut: @implementation

Code:

@implementation <#class#>

<#methods#>

@end

Objective-C dealloc Method

Shortcut: dealloc

Code:

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

Objective-C Fast Enumeration

Shortcut: forin

Code:

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

Objective-C Finally Block

Shortcut: @finally

Code:

@finally {
    <#handler#> }

Objective-C init Method

Shortcut: init

Code:

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

Objective-C KVO: Observe Value For Keypath

Shortcut: observeValueForKeyPath

Code:

- (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:

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

Objective-C Protocol Definition

Shortcut: @protocol

Code:

@protocol <#protocol name#> <NSObject>

<#methods#>

@end

Objective-C Try / Catch Block

Shortcut: @try

Code:

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

Struct Declaration

Shortcut: structdef

Code:

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

Switch Statement

Shortcut: switch

Code:

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

Test Method

Shortcut: test

Code:

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

Union Declaration

Shortcut: uniondef

Code:

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

While Statement

Shortcut: while

Code:

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

Objective-C NSCoding initWithCoder Method

Shortcut: initWithCoder

Code:

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

Objective-C NSView initWithFrame Method

Shortcut: initWithFrame

Code:

- (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 ，typedof 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。

Posted by TracyYih - 9月 6 2013 
如需转载，请注明： 本文来自 Esoft Mobile

原文  http://esoftmobile.com/2013/09/06/xcode预置sinppets知多少/