IOS常用代码整理

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1、更改cell选中的背景

UIView *cellView = [[UIView alloc] init];
cellView.frame = CGRectMake(0, 0, 320, 44);
cellView.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"xxx.png"]];
cell.selectedBackgroundView = cellView;



2、截取屏幕图片

UIGraphicsBeginImageContext(CGSizeMake(xxx,xxx));
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *aImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
imageData = UIImagePNGRepresentation(aImage);


3、自定义字符串颜色,拷代码,可直接用

+ (UIColor *) colorWithHexString: (NSString *) stringToConvert
{
NSString *cString = [[stringToConvert stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] uppercaseString]; //去掉前后空格换行符
// String should be 6 or 8 characters
if ([cString length] < 6) return [UIColor redColor];
// strip 0X if it appears
if ([cString hasPrefix:@"0X"]) cString = [cString substringFromIndex:2];
if ([cString hasPrefix:@"#"]) cString = [cString substringFromIndex:1];
if ([cString length] != 6) return [UIColor redColor];
// Separate into r, g, b substrings
NSRange range;
range.location = 0;
range.length = 2;
NSString *rString = [cString substringWithRange:range];
range.location = 2;
NSString *gString = [cString substringWithRange:range];
range.location = 4;
NSString *bString = [cString substringWithRange:range];
// Scan values
unsigned int r, g, b;
[[NSScanner scannerWithString:rString] scanHexInt:&r];  //扫描16进制到int
[[NSScanner scannerWithString:gString] scanHexInt:&g];
[[NSScanner scannerWithString:bString] scanHexInt:&b];
return [UIColor colorWithRed:((float) r / 255.0f)
green:((float) g / 255.0f)
blue:((float) b / 255.0f)
alpha:1.0f];
}


4、压缩图片,所需参数,需要处理的图片,新图片的size

- (UIImage*)imageWithImageSimple:(UIImage*)image scaledToSize:(CGSize)newSize

{

    UIGraphicsBeginImageContext(newSize);

    [image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];

    UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return newImage;

}

5、得到Label的Size,根据Label的内容,字体,字体大小,宽度。一般用于求Label的高度。

+(CGSize)getSizeForLabel:(NSString *)str fontFamily:(NSString *)fontFamily fontSize:(CGFloat)fontSize width:(NSInteger)labelWidth{
UIFont *font = [UIFontfontWithName:fontFamily size:fontSize];
CGSize size = CGSizeMake(labelWidth,3000);
return [strsizeWithFont:font constrainedToSize:sizelineBreakMode:UILineBreakModeCharacterWrap];
}


6、将data转换成64位的二进制,一般用于图片的上传。

+(NSString*) base64Encode:(NSData *)data
{
static char base64EncodingTable[64] = {
'A', 'B','C', 'D', 'E','F', 'G', 'H','I', 'J', 'K','L', 'M', 'N','O', 'P',
'Q', 'R','S', 'T', 'U','V', 'W', 'X','Y', 'Z', 'a','b', 'c', 'd','e', 'f',
'g', 'h','i', 'j', 'k','l', 'm', 'n','o', 'p', 'q','r', 's', 't','u', 'v',
'w', 'x','y', 'z', '0','1', '2', '3','4', '5', '6','7', '8', '9','+', '/'
};
int length = [data length];
unsigned long ixtext, lentext;
long ctremaining;
unsigned char input[3], output[4];
short i, charsonline = 0, ctcopy;
const unsignedchar *raw;
NSMutableString *result;
lentext = [data length];
if (lentext < 1)
return @"";
result = [NSMutableStringstringWithCapacity: lentext];
raw = [data bytes];
ixtext = 0;
while (true) {
ctremaining = lentext - ixtext;
if (ctremaining <= 0)
break;
for (i = 0; i <3; i++) {
unsigned long ix = ixtext + i;
if (ix < lentext)
input[i] = raw[ix];
else
input[i] = 0;
}
output[0] = (input[0] &0xFC) >> 2;
output[1] = ((input[0] &0x03) << 4) | ((input[1] &0xF0) >> 4);
output[2] = ((input[1] &0x0F) << 2) | ((input[2] &0xC0) >> 6);
output[3] = input[2] &0x3F;
ctcopy = 4;
switch (ctremaining) {
case 1:
ctcopy = 2;
break;
case 2:
ctcopy = 3;
break;
}
for (i = 0; i < ctcopy; i++)
[result appendString: [NSStringstringWithFormat: @"%c", base64EncodingTable[output[i]]]];
for (i = ctcopy; i < 4; i++)
[result appendString: @"="];
ixtext += 3;
charsonline += 4;
if ((length > 0) && (charsonline >= length))
charsonline = 0;
}
return result;
}



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