记录有用的代码片段

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记录有用的代码片段

file2

it is a test file.

打印当前调用处堆栈信息：

void* fun_addrs[40];
int rel_size = 0;
char** fun_names;
rel_size = backtrace(fun_addrs, 40);
fun_names = backtrace_symbols(fun_addrs, rel_size);
for (int idx = 0; idx < rel_size; idx ++) {
  printf("%s\n", fun_names[idx]);
}
free(fun_names);

自定义系统NSLog输出：

#define NSLog(format, ...) do {\
fprintf(stderr, "<%s : %d> %s\n",\
        [[[NSString stringWithUTF8String:__FILE__] lastPathComponent] UTF8String],\
        __LINE__, __func__);\
(NSLog)((format), ##__VA_ARGS__);\
fprintf(stderr, "-------\n");\
} while (0)

判断当前对象有没有被释放掉：

Class currentClass = object_getClass(self.delegate);
if (currentClass == _originalClass) {
        // 如果delegate没有被释放
}

判断手机硬件型号：

#import <sys/utsname.h>

- (NSString*) deviceName
{
    struct utsname systemInfo;

    uname(&systemInfo);

    NSString* code = [NSString stringWithCString:systemInfo.machine
                                        encoding:NSUTF8StringEncoding];

    static NSDictionary* deviceNamesByCode = nil;

    if (!deviceNamesByCode) {

        deviceNamesByCode = @{@"i386"      :@"Simulator",
                              @"x86_64"    :@"Simulator",

                              @"iPod1,1"   :@"iPod Touch",      // (Original)
                              @"iPod2,1"   :@"iPod Touch 2G",   // (Second Generation)
                              @"iPod3,1"   :@"iPod Touch 3G",   // (Third Generation)
                              @"iPod4,1"   :@"iPod Touch 4G",   // (Fourth Generation)
                              @"iPod5,1"   :@"iPod Touch 5G",

                              @"iPhone1,1" :@"iPhone",          // (Original)
                              @"iPhone1,2" :@"iPhone 3G",       // (3G)
                              @"iPhone2,1" :@"iPhone 3GS",      // (3GS)
                              @"iPhone3,1" :@"iPhone 4",        //
                              @"iPhone3,2" :@"iPhone 4",
                              @"iPhone3,3" :@"iPhone 4",
                              @"iPhone4,1" :@"iPhone 4S",       //
                              @"iPhone5,1" :@"iPhone 5",        // (model A1428, AT&T/Canada)
                              @"iPhone5,2" :@"iPhone 5",        // (model A1429, everything else)
                              @"iPhone5,3" :@"iPhone 5c",       // (model A1456, A1532 | GSM)
                              @"iPhone5,4" :@"iPhone 5c",       // (model A1507, A1516, A1526 (China), A1529 | Global)
                              @"iPhone6,1" :@"iPhone 5s",       // (model A1433, A1533 | GSM)
                              @"iPhone6,2" :@"iPhone 5s",       // (model A1457, A1518, A1528 (China), A1530 | Global)
                              @"iPhone7,1" :@"iPhone 6 Plus",
                              @"iPhone7,2" :@"iPhone 6",

                              @"iPad1,1"   :@"iPad",            // (1th Generation)
                              @"iPad2,1"   :@"iPad 2",
                              @"iPad2,2"   :@"iPad 2",
                              @"iPad2,3"   :@"iPad 2",
                              @"iPad2,4"   :@"iPad 2",
                              @"iPad3,1"   :@"iPad 3",
                              @"iPad3,2"   :@"iPad 3",
                              @"iPad3,3"   :@"iPad 3",
                              @"iPad3,4"   :@"iPad 4",
                              @"iPad3,5"   :@"iPad 4",
                              @"iPad3,6"   :@"iPad 4",
                              @"iPad4,1"   :@"iPad Air",        // 5th Generation iPad (iPad Air) - Wifi
                              @"iPad4,2"   :@"iPad Air",        // 5th Generation iPad (iPad Air) - Cellular
                              @"iPad5,3"   :@"iPad Air2",       //
                              @"iPad5,4"   :@"iPad Air2",        //

                              @"iPad2,5"   :@"iPad mini 1G",
                              @"iPad2,6"   :@"iPad mini 1G",
                              @"iPad2,7"   :@"iPad mini 1G",
                              @"iPad4,4"   :@"iPad mini 2",
                              @"iPad4,5"   :@"iPad mini 2",
                              @"iPad4,6"   :@"iPad mini 2",
                              @"iPad4,7"   :@"iPad mini 3",
                              @"iPad4,8"   :@"iPad mini 3",
                              @"iPad4,9"   :@"iPad mini 3",

                              @"AppleTV2,1" : @"Apple TV 2G",
                              @"AppleTV3,1" : @"Apple TV 3G",
                              @"AppleTV3,2" : @"Apple TV 3G",
                              };
    }

    NSString* deviceName = [deviceNamesByCode objectForKey:code];

    if (!deviceName) {
        // Not found on database. At least guess main device type from string contents:

        if ([deviceName rangeOfString:@"iPod"].location != NSNotFound) {
            deviceName = @"iPod Touch";
        }
        else if([deviceName rangeOfString:@"iPad"].location != NSNotFound) {
            deviceName = @"iPad";
        }
        else if([deviceName rangeOfString:@"iPhone"].location != NSNotFound){
            deviceName = @"iPhone";
        }
        else if ([deviceName rangeOfString:@"AppleTV"].location != NSNotFound) {
            deviceName = @"AppleTV";
        } else if ([deviceName rangeOfString:@"86"].location != NSNotFound) {
            deviceName = @"Simulator";
        }
    }

    return deviceName;
}

参考：http://stackoverflow.com/questions/11197509/ios-iphone-get-device-model-and-make

系统版本判断：

#define SYSTEM_VERSION_EQUAL_TO(v)                  ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedSame)
#define SYSTEM_VERSION_GREATER_THAN(v)              ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedDescending)
#define SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(v)  ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] != NSOrderedAscending)
#define SYSTEM_VERSION_LESS_THAN(v)                 ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedAscending)
#define SYSTEM_VERSION_LESS_THAN_OR_EQUAL_TO(v)     ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] != NSOrderedDescending)

参考：https://github.com/carlj/CJAMacros/blob/master/CJAMacros/CJAMacros.h

swift查看底层：

swift -dump-ast  swiftname

/Applications/Xcode6-Beta2.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift  -dump-ast  a.swift

打印当前window的层次：

 po [[[UIApplication sharedApplication] keyWindow] recursiveDescription] 

• iOS5及以上版本layout放在：

viewWillLayoutSubviews:

或

viewDidLayoutSubviews: 

• iOS4系统layout放在：

layoutSubviews

计算文本区域：

+ (CGSize)sizeOfString:(NSString *)string font:(UIFont *)font size:(CGSize)size
{
    CGSize stringSize = CGSizeZero;
    if (SYSTEM_VERSION_LESS_THAN(@"7.0")) {
        stringSize = [string sizeWithFont:font
                        constrainedToSize:size
                            lineBreakMode:UILineBreakModeWordWrap];
    } else {
        stringSize = [string boundingRectWithSize:size
                                          options:NSStringDrawingTruncatesLastVisibleLine | NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading
                                       attributes:font.fontDescriptor.fontAttributes
                                          context:nil].size;
    }

    return stringSize;
}

更改UIToolBar背景色

if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(@"7.0")) {
        toolBar.translucent = NO;
        toolBar.barTintColor = [UIColor whiteColor];
 }

四舍五入保留两位小数

float a = 3.456; //保留到小数点后两位
float b =(int)((a * 100) + 0.5) / 100.0;

//output b = 3.46;

不同view继承体系之间区域转换

例如一个视图控制器的view中有一个UITableView，UITableView的某个cell中有个UITextField，想要得到UITextField在view中的位置：

CGRect rect = [self.view convertRect:textField.frame fromView:textField.superview];
//或者
CGRect rect = [textField.superview convertRect:textField.frame toView:self.view];

不同view继承体系之间点转换

• 把一个点从一个坐标系转换到接收者的坐标系

- (CGPoint)convertPoint:(CGPoint)point fromView:(UIView *)view

参数
point
一个视图中坐标系上的点
view
一个视图包含了点和他自身坐标系。如果是图是nil，那么这个方法将尝试转换基于窗口的坐标系。否则视图和那个接收者必须属于同一个UIWindow对象。

• 转换一个点从接收者坐标系到给定的视图坐标系

- (CGPoint)convertPoint:(CGPoint)point toView:(UIView *)view

参数
point
一个在调用者坐标系中的点
view
一个包含了需要被转换的点的视图。如果视图是nil，那么这个方法将会转换成基于窗口的坐标。否则视图和接收者都要属于同一个UIWindow对象。
返回值

Block 使用方式

How Do I Declare A Block in Objective-C?

• As a local variable:

returnType (^blockName)(parameterTypes) = ^returnType(parameters) {...};

• As a property:

@property (nonatomic, copy) returnType (^blockName)(parameterTypes);

• As a method parameter:

- (void)someMethodThatTakesABlock:(returnType (^)(parameterTypes))blockName;

• As an argument to a method call:

[someObject someMethodThatTakesABlock:^returnType (parameters) {...}];

• As a typedef:

typedef returnType (^TypeName)(parameterTypes);
TypeName blockName = ^returnType(parameters) {...};

URL:
http://goshdarnblocksyntax.com/