Xcode-Snippets/Objective-C 学习

前言

Xcode-Snippets是github上的一堆开源代码。作者mattt分享了他的Xcode-Snippets(xcode代码片段)，今天我们来学习一下。

片段

singleton.m

+ (instancetype)shared<#name#> {
    static <#class#> *_shared<#name#> = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        _shared<#name#> = <#initializer#>;
    });

    return _shared<#name#>;
}

单例，标准代码。

stack.m

NSLog(@"Call Stack: %@", [NSThread callStackSymbols]);

这个有点意思，输出线程的调用栈？不知道是不是真么翻译。输出如下：

Call Stack: (
    0   Countdown                           0x00000001000a73e4 -[AppDelegate application:didFinishLaunchingWithOptions:] + 120
    1   UIKit                               0x0000000186aeb124 <redacted> + 404
    2   UIKit                               0x0000000186d027e8 <redacted> + 2376
    3   UIKit                               0x0000000186d0519c <redacted> + 1504
    4   UIKit                               0x0000000186d0370c <redacted> + 184
    5   FrontBoardServices                  0x000000018a83d3c8 <redacted> + 32
    6   CoreFoundation                      0x0000000181fb827c <redacted> + 20
    7   CoreFoundation                      0x0000000181fb7384 <redacted> + 312
    8   CoreFoundation                      0x0000000181fb59a8 <redacted> + 1756
    9   CoreFoundation                      0x0000000181ee12d4 CFRunLoopRunSpecific + 396
    10  UIKit                               0x0000000186ae43d0 <redacted> + 552
    11  UIKit                               0x0000000186adef40 UIApplicationMain + 1488
    12  Countdown                           0x000000010013177c main + 124
    13  libdyld.dylib                       0x0000000194326a08 <redacted> + 4
)

strongself.m && weakself.m

__strong __typeof(<#weakSelf#>)strongSelf = <#weakSelf#>;
__weak typeof(self)weakSelf = self;

这个没啥好说的，用于防治block中循环引用。

tu.m

醉了

UIControlEventTouchUpInside

tvdel.m && tvds.m

这两个也醉了，不过蛮实用

#pragma mark - UITableViewDelegate

- (void)tableView:(UITableView *)tableView
didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    <#statements#>
}

#pragma mark - UITableViewDataSource

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    return <#number#>;
}

- (NSInteger)tableView:(UITableView *)tableView
 numberOfRowsInSection:(NSInteger)section
{
    return <#number#>;
}

- (UITableViewCell *)tableView:(UITableView *)tableView
         cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:<#reuseIdentifier#> forIndexPath:<#indexPath#>];

    [self configureCell:cell forRowAtIndexPath:indexPath];

    return cell;
}

- (void)configureCell:(UITableViewCell *)cell
    forRowAtIndexPath:(NSIndexPath *)indexPath
{
    <#statements#>
}

xae.m xaf.m xan.m xann.m xat.m

断言调试宏，分别对应
e-Equel
f-False
n-Nil
nn-NotNil
t-True

async.m

GCD的异步等待嵌套。

dispatch_async(dispatch_get_global_queue(<#dispatch_queue_priority_t priority#>, <#unsigned long flags#>), ^(void) {
    <#code#>

    dispatch_async(dispatch_get_main_queue(), ^(void) {
        <#code#>
    });
});

cdfetch.m

CoreData的fetch代码，其实官方自带的。

NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] initWithEntityName:<#entityName#>];
fetchRequest.predicate = [NSPredicate predicateWithFormat:<#predicateFormat#>];

NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:<#key#> ascending:<#isAscending#> selector:<#selector#>];
fetchRequest.sortDescriptors = @[sortDescriptor];

NSError *error;
NSArray *results = [<#context#> executeFetchRequest:fetchRequest error:&error];

if (error) {
    NSLog(@"%@", error);
}

官方版本

NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"<#Entity name#>" inManagedObjectContext:<#context#>];
[fetchRequest setEntity:entity];
// Specify criteria for filtering which objects to fetch
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"<#format string#>", <#arguments#>];
[fetchRequest setPredicate:predicate];
// Specify how the fetched objects should be sorted
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"<#key#>"
                                                              ascending:YES];
[fetchRequest setSortDescriptors:[NSArray arrayWithObjects:sortDescriptor, nil]];

NSError *error = nil;
NSArray *fetchedObjects = [<#context#> executeFetchRequest:fetchRequest error:&error];
if (fetchedObjects == nil) {
   <#Error handling code#>
}

checkerror.m

注释说用于把OSStatus error翻译成人类能看懂的语言。

static void CheckError(OSStatus error, const char *operation) {
    if (error == noErr) {
      return;
    }

    char str[20];
    *(UInt32 *) (str + 1) = CFSwapInt32HostToBig(error);
    if (isprint(str[1]) && isprint(str[2]) && isprint(str[3]) && isprint(str[4])) {
        str[0] = str[5] = '\'';
        str[6] = '\0';
    } else {
        sprintf(str, "%d", (int)error);
    }

    fprintf(stderr, "[Error] %s (%s)\n", operation, str);
    exit(1);
}

continuation.m

快速在.m文件添加匿名Category

@interface <#Class Name#> ()
<#Continuation#>
@end

cvds.m

尿性

#pragma mark - UICollectionViewDataSource

- (NSInteger)collectionView:(UICollectionView *)collectionView
     numberOfItemsInSection:(NSInteger)section
{
    return <#numberOfItemsInSection#>;
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView
                  cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:<#reuseIdentifier#> forIndexPath:indexPath];

    [self configureCell:cell forItemAtIndexPath:indexPath];

    return cell;
}

- (void)configureCell:(UICollectionViewCell *)cell
   forItemAtIndexPath:(NSIndexPath *)indexPath
{
    <# statements #>
}

documents.m

取App下Documents文件夹路径，还算实用

NSURL *documentsDirectoryURL = [NSURL fileURLWithPath:[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject]];

frame.m

这个比较6。用语法糖实现，66666

<# view #>.frame = ({
    CGRect frame = <# view #>.frame;
    <# ... #>
    frame;
});

frc.m

NSFetchedResultsController是个好东西。

NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] initWithEntityName:<#(NSString *)#>];
fetchRequest.predicate = [NSPredicate predicateWithFormat:<#(NSString *), ...#>];
fetchRequest.sortDescriptors = @[<#(NSSortDescriptor *), ...#>];

NSFetchedResultsController *fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:<#(NSFetchRequest *)#> managedObjectContext:<#(NSManagedObjectContext *)#> sectionNameKeyPath:<#(NSString *)#> cacheName:<#(NSString *)#>];
fetchedResultsController.delegate = <#(id <NSFetchedResultsControllerDelegate>)#>;

NSError *error = nil;
if (![fetchedResultsController performFetch:&error]) {
    NSLog(@"Error: %@", error);
}

frcd.m

NSFetchedResultsController的一堆回调

imv.m

这..

[[UIImageView alloc] initWithImage:[UIImage imageNamed:@"<#image name#>"]]

init.m

顾名思义了,不过是强迫症写法

self = [super init];
if (!self) {
  return nil;
}

<#initializations#>

return self;

library.m

Library路径

[NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES) firstObject];

lifecycle.m

最实用，没有之一

#pragma mark - UIViewController

- (void)viewDidLoad {
    [super viewDidLoad];
}

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
}

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
}

- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
}

- (void)viewDidDisappear:(BOOL)animated {
    [super viewDidDisappear:animated];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
}

mailcomp.m

调用系统邮件UI

#import <MessageUI/MessageUI.h>

- (void)presentModalMailComposerViewController:(BOOL)animated {
    if ([MFMailComposeViewController canSendMail]) {
        MFMailComposeViewController *composeViewController = [[MFMailComposeViewController alloc] init];
        composeViewController.mailComposeDelegate = self;

        [composeViewController setSubject:<#Subject#>];
        [composeViewController setMessageBody:<#Body#> isHTML:YES];
        [composeViewController setToRecipients:@[<#Recipients#>]];

        [self presentViewController:composeViewController animated:animated completion:nil];
    } else {
        [[[UIAlertView alloc] initWithTitle:NSLocalizedString(@"Error", nil) message:NSLocalizedString(@"<#Cannot Send Mail Message#>", nil) delegate:nil cancelButtonTitle:NSLocalizedString(@"OK", nil) otherButtonTitles:nil] show];
    }
}

#pragma mark - MFMailComposeViewControllerDelegate

- (void)mailComposeController:(MFMailComposeViewController *)controller
          didFinishWithResult:(MFMailComposeResult)result
                        error:(NSError *)error
{
    if (error) {
        NSLog(@"%@", error);
    }

    [self dismissViewControllerAnimated:YES completion:nil];
}

mark.m

短，然并卵

#pragma mark - <#Section#>

跟直接输入有什么区别。

nscoding.m

NSCoding协议实现相关方法

#pragma mark - NSCoding

- (instancetype)initWithCoder:(NSCoder *)decoder {
    self = [super init];
    if (!self) {
      return nil;
    }

    <# implementation #>

    return self;
}

- (void)encodeWithCoder:(NSCoder *)coder {
  <# implementation #>
}

nsl.m

短，然并卵2，本地化字符串

NSLocalizedString(@"<#Message#>", <#Comment#>)

pdel.m && pds.m

UIPickerView的回调

#pragma mark - UIPickerViewDelegate

- (NSString *)pickerView:(UIPickerView *)pickerView
             titleForRow:(NSInteger)row
            forComponent:(NSInteger)component
{
  <#code#>
}

- (void)pickerView:(UIPickerView *)pickerView
      didSelectRow:(NSInteger)row
       inComponent:(NSInteger)component
{
  <#code#>
}

#pragma mark - UIPickerDataSource

- (NSInteger)pickerView:(UIPickerView *)pickerView
numberOfRowsInComponent:(NSInteger)component
{
  return <#number#>
}

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {
  return <#number#>
}